Spark-plug gasket.



R. A. STRANAHAN.

' SPARK PLUG GASKET.

APPLICATION FILED OCT. 25, 1915.

Patented June 20, 1916.

INVE'N-TUH drawings, in which,

To s'ra'rns rarnn'r orr 'ron ROBERT A. STBANAHAN, OF TOLEDO, OHIO, .ASSIGNOR TO CHAMPION SPARK PLUG COMPANY, OF TOLEDO, OHIO, CORPORATION OF MASSACHUSETTS.

SPARK-PLUG GASKET.

Specification of Letters Patent.

Patented June 20, Mild.

Application filed October 28, 1915. Serial No. 58,355.

To all wkomz't may concern Be it known that 1, ROBERT A. STRANA- HAN, a citizen of the United States, and a resident of Toledo, in the county of Lucas and State of Ohio, have invented a certain new and useful Spark-Plug Gasket; and 1 do hereby declare the following to be a'full, clear, and exact description of the invention,

such as will enable others skilled in the art I to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the characters of reference marked thereon, which form a part of this specification.

This invention relates to spark plugs and particularly to a gasket for use therein.

The object of, my invention is the provision of a gasketof the character described, which is adapted not only to form a gas tight joint between portions of the shell and porcelain, but also to effect a perfect centering of the spark plug parts when assembled whereby to simplify, cheapen and facilitate the assembling of spark plugs.

The invention is fully described in the following specification, and while, in its broader aspect, it is capable of embodiment in numerous forms, a preferred embodiment thereof is illustrated in the accompanying Figure 1 is a central longitudinal section of a spark plug embodying my invention with the porcelain in full. Fig. 2 is a cross section of the gasket embodying the invention, Fig. 3 is a plan view of the channeled side thereof with the packing material removed, and Fig. 4 is a sectional view of a slightly modified form of the invention.

Referring-to the'drawings, 1 designates the customary body shell of a spark plug, which shell is provided with an externally threaded end portion 2 for threading in the spark plug receiving hole of an engine cylinder, and which carries an electrode 3. The shell 1 is provided lengthwise thereof with an axial opening 4 which is enlarged at its outer end, as at 5, with the bottom of such enlarged portion formed with a preferably tapered annular shoulder 6.

The porcelain 7 of the spark plug has one end inserted into the shell opening to near the inner end thereof and in spaced relation to its wall, and is provided intermediate its ends with an annular enlargement 8 forming shoulders 9 and 10 at the inner and outer ends thereof, respectively. The porcelain carries the center electrode 11, as is customary. n

The gasket 12 forming the present inven tion is disposed, in the present instance, be. tween the shoulders 6 and 9 of the shell and porcelain, respectively, and comprises a metal part a of sheet copper or other suitable material a nd of ring form, the inner and outer edges of which are flanged. in the same direction, as shown at 7), and 0, respectively, to form the part a with a channel in which a packing part d, of asbestos or other suitable material, is disposed. The purpose mainly of the inner flange b is to retain the packing part in position and may therefore be of shallow form or turned outwardly over the edge of the packing material as shown at e in Fig. 4. The outer flange 0 is preferablydeeper than the outer edge of the packing material (Z to adapt it to project outward relative to the shell in radially spaced encircling relation to the enlargement 8 of the porcelain as shown in Fig. 1. The center opening of the gasket is of suitable size to adapt it to fit closely around the porcelain at the side of the enlargement 8 for which it is intended, while the diameter of the gasket is such as to adapt the flange 0 to fit closely against'the side Wall of the enlarged portion of the shell opening. In practice theporcelain 7 and shell opening should be of different sizes to provide an air space between the two so that the porcelain is not liable to be injured by a contraction of the metal under changing temperature conditions. It is also important to have the outer flange portion 0 of the gasket 12 spaced from the porcelain so as to allow for contraction of the metal shell relative to the porcelain.

The porcelain is retained assembled within the shell 1 by a follower nut 13 screw ing into the outer end of the shell against a gasket 14:, which seats on-the adjacent end of the porcelain enlargement 8, or the parts may be retained assembled in any other suitable manner. The provision of a gasket like the gasket 12, which is in holding engagement at its inner edge with the a porcelain and is of suitable size for its outer edge to fit closely into the shell 1 in preferably spaced relation to the porcelain is an important feature in connection with the assembling of the parts of spark plugs, as

the gasket is not only itself truly centered with respect to the shell, but serves to center the porcelain within the shell, thereby preventing a lop-sided seating of the porcelain within the shell when the holding parts of the shell are tightened thereagains t.

, It is found in practice that a tighter and more perfect joint is not only provided be-' tween the seating parts of a spark plug by maintaining a gasket in centered position,

but also that the air space between the shell and porcelain is maintained entirely therearound so that the porcelain is not liable to be injured by contact with the metal of the shell.

WVhile the part 7 of the spark plug has been generally referred to as a porcelain, it will be understood that the term porcelain as used herein has reference broadly.

. departing from the spirit of the claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is-

1. The combination withthe shell and 'porcelainof a spark plug, of a gasket having a metallic part of ring form provided with inner and outer flanges projecting in the same general direction in transversely spaced relation with respect to the spark plug axis and with the inner flange closely fitting the porcelain and the outer flange closely fitting within the shell whereby to center the porcelain within the shell.

2. The combination with the shell and porcelain of a spark plug, of a gasket of ring form having a metal part provided at its edges with upstanding flanges formin a channel with the opening of saidpart 0 suitable size to fit closely around a porcelain and with the outer edge of said part of a size to fit closely Within the shell whereby to center the porcelain therein, and. a packing material disposed in the channel of said metallic part.

3. The combination with the shell and porcelain of a spark plug, of a centerin gasket therefor disposed between opposed seating portions of the shell and porcelain and having inner and outer flanges'projecting in the same general direction length wise of the spark. plug and with the inner flange fitting closely around the porcelain and with the outer, flange fitting closely within the shell and, radially s aced from the portion of the porcelain w ich it en:

circles,,and a packing material carried b the gasket in the channel formed by sai flanges.

ln testim ony whereof I have hereunto signed my name .to this specificatibriL.

ROBERT A. STRANAHAN. 

